1. Field of the Invention
The present invention pertains to metal frames and frame assemblies for doors or other casings and in particular to means of attaching metal door and window frame headers to jambs.
2. Description of Related Art
The field of the present invention is the art of metal frames for openings, such as doors in buildings and the invention may also be applied to window frames and casings as well. More particularly, this invention relates to hollow sheet metal frames which can be easily installed by workmen in openings, such as the doorway in a new or an existing wall of a building. Typically simple tools, for example, a hammer, level, a square and screw driver are used for assembly installation. The frames may be delivered either assembled or in knockdown condition for field assembly at the job site. When assembled, the ends of the header and the adjacent ends of the jambs are arranged to be in close fitting relation and are secured together by means which prevent them from loosening up and ends from becoming dislodged. The engaged ends of the header and jamb resist distortion, dislodgement, and relative movement by reason of their interengagement and reinforcements therein. Metal doors are particularly suited for masonry wall construction.
U.S. Pat. Nos. 2,741,344, 3,429,076, and 3,552,085 are typical of the prior art techniques used to attach the door jambs and headers at their common ends at the upper corners of the frame. A problem encountered by architects and builders is crevices or openings between the soffit and stop surfaces of the mated jambs and headers of the assembled frames in the corner mitered joints. They are visible to people passing through the door, are an architectural eyesore that detracts from the aesthetic appeal of the doorway, and can be bent if accidently caught by or on something. Therefore it is highly desirable to have a mitered corner joint as well as a butted corner joint along the soffits of the mated jambs and headers that tightly attaches the header to the jamb and reduces or eliminates the openings between the soffits.